I am using Windows 10 OS. If I create a new Writer file on desktop, I get the blue icon of Writer. If I type and save the document, the icon changes to LibreOffice white. It does not happen if writer is opened in other folders in C drive and this problem is only with regard to desk top. Calc icon does not give this problem. Can this issue be resolved?
You should not be saving to the desktop because in the event of having to wind Windows back a day or two with System Restore, then the desktop will be restored to the earlier version, that is, it might not have the document at all, or it might be the document before two days of editing.
The Documents folder is unaffected by System Restore.
The answer is that only small icons are blue, all other sizes use the thumbnail picture of the document embedded in the file.
Here is an experiment, open File Explorer (press Win+E). Navigate to a folder with some Open Document Format (ODF) files in it, e.g. your Desktop. Maybe you see your files in Details view, change to medium icons and watch the icons change to the thumbnail.
You could try the steps in this third party site, https://www.thewindowsclub.com/enable-or-disable-thumbnail-previews-in-explorer